“It takes little imagination to consider that the pre-Cambrian mass extinction event(s) was correlated with the impact of a giant life-bearing comet (or comets), and the subsequent seeding of Earth with new cosmic-derived cellular organisms and viral genes,” that hitched a ride to Earth on icy bolides. “Indeed,” this principle applies to the sudden appearance in the fossil record of pretty well all major life forms.”

Cephalopods – octopuses, squids and nautiluses – “are an island of mental complexity in the sea of invertebrate animals” having developed on a different path from us, “an independent experiment in the evolution of large brains and complex behavior," says Godfrey-Smith, philosopher of science. “If we can make contact with cephalopods as sentient beings, it is not because of a shared history, not because of kinship, but because evolution built minds twice over,” adds Godfrey-Smith. “This is probably the closest we will come to meeting an intelligent alien.”

Our Earthly aliens –a group of 33 scientists from respected institutions around the world have suggested Octopuses descended from organic alien material, reports Newsweek. Their research, published in the journal Progress in Biophysics and Molecular Biology, ties the “remarkable” rise of octopuses and their cephalopod cousins to the theory of panspermia.

Acknowledged experts are unconvinced by the findings. Avi Loeb, the Frank B. Baird Jr. Professor of Science at Harvard University, told Newsweek the study raised "an interesting but controversial possibility, offering no "indisputable proof" that the Cambrian explosion is the result of panspermia.

Astrobiologist Frances Westall, who is involved in the European Space Agency's Mars Express mission, is very skeptical of the paper. For instance, some microbial cells and seeds, she told Newsweek, have been shown to survive in space for certain periods of time. But in the scenario offered in this paper, they would need to have survived for thousands of years.

Although the chemical building blocks for life may be cosmic, more experimental work needs to be done to probe the origins of life on Earth, Westall said. "Unfortunately it is all too easy to pull information out of the literature to support one's hypothesis," she added. "Nature is incredible, and I do not think it is necessary to call on extraterrestrials to explain.